16 • REMARKS ON TEMPERATURE OF THE EARTH IX MINES. 



a wooden partition divides the sliaft into two equal compart- 

 ments three feet square each, and a very sUght imperceptible 

 amount of ventilation was produced. The sliaft is 1,200 feet in 

 depth. The temperature at the surface at lOh. 30m. a.m. 

 was 90 degs., whilst that at the bottom was 78 degs. Thus 

 showing an average decrease of temperature of 1 degree to each 

 100 feet. This being so diverse from the commonly received 

 theory caused other observations to be made, which appear to 

 indicate that that theory is not universally applicable ; and, on 

 looking up other records, it is evident that local causes m most 

 cases sufficiently account for the increment of temperature 

 which has been observed. 



At the Golden Cro'\^al shaft on same day (14th December), 

 at 3h. 15m. p.m., the temperature in the shadiest of places at 

 the surface was 90 degs. ; at 240 feet down the shaft it was 

 78 degs.; at 420 it was also 78 degs.; at 1,090 it was 80 

 degs. ; and at 1 ,200 also 80 degs. The 290 feet level 

 communicates ^yith another shaft, but none of the other places 

 have any such communication ; the shaft is centred, men were 

 at work at the bottom — i.e., at 1,200 feet, opening out, leaving 

 a well-hole of 30 feet, no ventilating apparatus of any kind is 

 in use, and therefore the bottom of the shaft would be hotter 

 than its normal condition ; yet it was IG degs. below the 

 temperature of the coolest place to be found at the surface 

 where abimdant shade is found, and only 2 degs. hotter than 

 the 240 feet level nearly 1,000 feet above, where the advantage 

 of through communication with another shaft was obtained. 



On 15th December, at the Great Monkland, the weather 

 had materially altered from that of the previous day, a little rain 

 had fallen, and a slight mist hung in a cloudy atmosphere ; 

 again the shadiest place was taken, and the hour was 8 a.m., 

 temperature 80 degs. ; went direct to the 1400 feet opening and 

 found it 70 degs., the shaft was centered, but no artificial means 

 of producing a current was used ; the centering was carried 5 

 feet below this opening. At 1450 feet, the depth to which the 

 shaft had then reached, two men were at work ; the centering 

 was 45 feet above, and the place kept continually warm by three 

 shifts, of two men each, working, whose chief duty is boring and 



